1. Field of the Invention
This invention relates generally to deceleration control systems for vehicles, and more particularly concerns a monitor for controlling uncommanded braking of one or more wheels of an aircraft during takeoff that also permits the use of a single microproprocessor to perform all brake control functions.
2. Description of Related Art
Automatic braking systems have been commonly provided on commercial aircraft to aid the deceleration of the aircraft upon landing. As the size and complexity of aircraft have increased, the automatic braking systems have also become more complex and computerized. Modern anti-skid systems incorporated into aircraft braking systems commonly optimize braking efficiency by adapting to runway conditions and other factors which affect braking in order to optimize deceleration, typically corresponding to the level of brake pressure selected by the pilot.
A catastrophic failure mode has been identified in one such conventional single microproprocessor controlled brake-by-wire control system that results in uncommanded brake application on one or more wheels during takeoff of the aircraft. Since uncommanded braking during takeoff can have serious consequences, and at the very least can result in unnecessary and accelerated wear to the braking system, it is desirable to configure the braking system to reduce the possibility of these undesirable results. Conventional brake control systems having this type of catastrophic failure mode typically require a second channel for monitoring and backup of the brake control system to prevent uncommanded braking.
One conventional approach to overcoming the failure of the control system has been the implementation of a multiple processor microcontroller design utilizing D0178A level 1 or D0178B level A software. However, the costs of implementing a multiple microprocessor controller design are significantly greater than that for a control system utilizing a single microprocessor. It is highly desirable to provide a monitor for uncommanded braking to prevent uncommanded braking during takeoff of an aircraft. It would also be desirable to provide such a monitor for uncommanded braking that is implemented in hardware rather than in software with multiple processors. The present invention meets these needs.